The present invention relates to a method of controlling an elevator installation which comprises an elevator car transporting passengers between floors of a building. The method proposes that the travel wishes of the passengers are input by way of a destination call control and booked by the destination call control as destination calls. In addition, an instantaneous load disposed in the elevator car is determined by a load measuring device at a fixable point in time. The invention further relates to an elevator installation which is provided with an elevator car, a load measuring device determining an instantaneous load disposed in the elevator car and a destination call control by means of which travel wishes of passengers to be transported can be input and booked as destination calls.
In high buildings, particularly in so-termed skyscrapers, elevators are used which are controlled by a destination call control. In that case the travel destination must be input by way of a numerical keyboard or another form of input means by every passenger before the start of travel. The control of the elevator installation notifies the passenger, on the basis of his or her travel destination input, an elevator which guarantees for the passenger an optimized travel time. An elevator installation with destination call control is described in, for example, the published application WO 01/72621 A1. The basis for functioning of an elevator installation based on a destination call control is a disciplined input of destination calls.
However, a disciplined behavior of that kind of the passengers cannot always be presupposed. Situations can arise that only one person of a group undertakes a destination call input or it can happen that one person puts in several destination call inputs for a group, wherein, however, the number of persons does not correspond with the number of destination call inputs. This undisciplined input of destination calls in which the destination call control is not correctly operated frequently occurs when many persons have to be transported at the same time from a floor to, for example, the ground floor, wherein the bulk of passengers know that all elevators travel in the direction of the ground floor. An undisciplined input of destination calls can accordingly be regularly established when fixed working times exist and many office workers of a company leave their office spaces at almost the same time in order to travel to the ground floor. The elevator cars are thereby usually fully laden already in the upper floors without every passenger having individually booked his or her travel destination by means of the destination call input. The destination call control undertaking allocation of the elevators proceeds only from the booked destination calls.
The problem therefore results that destination call inputs of passengers in the floors lying further down are allocated to elevator cars which are fully loaded, so that these passengers cannot be transported by the allocated elevator car. However, notwithstanding the full load the elevator car stops at every floor at which a destination call input was registered and a destination call allocated to the corresponding elevator car. This can lead to the situation that a passenger who would like to disembark at a floor above the ground floor is allocated an already fully loaded elevator car. The elevator car then stops at the floor at which the passenger proposes to board, but the passenger cannot since the elevator car is full. The elevator car consequently also stops at the floor at which the passenger wanted to disembark, although nobody does disembark.
Due to the undisciplined inputs of destination calls substantial increases in transport times arise and ultimately this leads to a reduction in transport capacity, which leads to very long waiting times particularly in buildings with an otherwise small transport capacity.
A group control for elevators is described in European patent document EP 0 301 173 A1 which has a monitoring circuit preventing allocation of a destination call to an elevator with an overload. However, the starting point is a careful input of destination calls, since the overload is determined on the basis of booked passengers.
In PCT published application WO 03/026997 A1 there is described an elevator installation in which the elevator load is measured by continuous load measuring so that the number of passengers who have not input a destination call input can be determined.